GB1120981A - Method and apparatus for measuring the length of irregularities in the thickness of atextile yarn - Google Patents

Abstract

1,120, 981. Measuring the length of irregularities in thickness of yarn. W. REINERS. July 7, 1965 [July 9, 1964], No.28817/65. Headings G1A and G1N. A method of measuring the length of irregularities in thickness (slubs) in a textile yarn, involves making measurements capacitatively or photo-electrically, at a number portions of the yarn located adjacent one another in the direction of yarn movement, to produce values dependent on the dimensions of the yarn at those points, obtaining logarithms of these measurements and adding the logarithms together. The apparatus may comprise a set of photo-cells E 1 -E 4 (Fig. 3a) across which the yarn passes in front of a beam of light or (Fig. 3b) a set of separate capacitor plates C 1 -C 4 , arranged opposite a common plate C 5 , the yarn passing between the set and the common plate. In the photo-electric arrangement, for example, the output of each cell, representing the degree of illumination of the cell which depends on the dimensions of yarn or yarn slub interposed between it and the light, is fed to a circuit Fig. 5 or Fig. 6 (not shown) to transform the signal into a logarithmic one. The logarithmic signals from all four cells are combined in a summation circuit Fig. 9 (not shown) and the output of this is applied to a recording or monitoring device or to the input of a yarncutting device control circuit Fig. 11 (not shown) for an automatic yarn-cleaning apparatus. The combined logarithmic signal contains information as to the volume of a slub and as to its length (i.e. the number of photo-cells it overlaps) and is supplied to oppose a predetermined voltage representing the maximum allowable slub length or volume. If the logarithmic signal voltage exceeds the predetermined voltage, a transistor (16) is switched on and a yarn severing device activated. The predetermined voltage is set by means of three variable resistors determining yarn thickness, and the thickness and length of permissible irregularities. If the photodetectors are of the silicon type with an exponentially varying output, a special circuit is provided to convert this into a linear signal before the logarithmic conversion Fig. 8 (not shown). A circuit is also described for converting the combined logarithmic signal into an exponential signal which can be used to control yarn severing apparatus Fig. 10 (not shown).